1. Field of the Invention
This invention relates to filled polymeric masses and more particularly relates to filled thermoplastic polymer matrixes and to additives integrally added to the filler thermoplastic polymer blend for conserving or enhancing the physical properties of the filled thermoplastic polymer including improved impact strength. The invention also relates to novel integral additives for addition to filler thermoplastic polymer blends for providing improved processing characteristics to the blend such as lower pressures required to fill molds in an injection molding operation. The invention also provides methods for producing reinforced or filled thermoplastic polymers of improved physical properties and relates to the resulting improved filled thermoplastic polymers.
2. Description of the Prior Art
A very extensive amount of research has been performed on the treatment of fillers or reinforcing agents for synthetic polymers including thermoplastic polymers such as polyethylene, polypropylene and the like.
Most recently, U.S. Ser. No. 295,812 filed on Aug. 27, 1981 taught the synergistic result of blending a thermoplastic organic polymer with an inorganic filler, a polymerizable unsaturated organic compound, a vinyl-polymerizable unsaturated hydrolyzable silane and a surfactant. The general teachings of the art prior to this invention had generally discouraged the addition of surfactants to polymer-filler blends. Although this blend resulted in certain improvements in the physical and processing properties of the resultant filled thermoplastic polymer matrix, there continues a need for even greater improvements in these physical and processing characteristics.
Prior to the conception of U.S. Ser. No. 298,812 it had been known to employ free radical generators to decrease the duration and/or amount of melt processing necessary to obtain desirable results. U.S. Pat. No. 3,471,439 particularly points out the advantages that a free radical generator can lend to a reinforcing filler. This inference fails however to teach or suggest the use of a surfactant in the filled thermoplastic polymer matrix.
Other references of interest include U.S. Pat. No. 4,104,289 which teaches the use of trivinylisocyanurate with peroxide to improve the mechanical properties of filled polyethylene. U.S. Pat. No. 3,556,754 which teaches the use of a vinyl-polymerizable unsaturated hydrolyzable silane with a siloxane oxyalkylene block copolymer as a glass treatment and how compounding with a resin in the presence of a peroxide produces superior molded composites. U.S. Pat. No. 3,806,555 which discloses the crosslinking of an olefin polymer or copolymer in the presence of peroxide. U.S. Pat. No. 4,317,765 which describes the mixing of a polyolefin, a filler, maleic anhydride and a peroxide to form a composite having improved mechanical properties.
None of the prior art references identified above disclose or suggest any method that involves the synergistic results obtained by the addition of a surfactant of the type described herein with a free radical generator to a mixture of thermoplastic polymer, blending additives, and filler for the purpose of improving processing characteristics such as pressure-to-fill requirements and conserving or enhancing physical properties.